Electron-discharge device



Aug. 7, 1923. 1,463,860

W. WILSON ELECTRON DISCHARGE DEVICE 7 Filed July 22, 1920 Will/b M7500.

Patented Aug. 7, 1923.

- UNITED STATES PATENT OFFICE.

WILLIAM WILSON, ,OF HAPLEWOOD, NEW JERSEY, ABSIGNOR TO WESTERN ELECTRIC COMPANY INCORPORATED, 03 NEW YORK, N. Y., A CORPORATION 01' NEW YORK.

ELECTRON-DISCHARGE DEVICE.

Application filed July 22, 1920. Serial ll'o. 398,897. 4

To all whom it may concern.

B it known that I, WILLIAM WILSON, a subject of the King of Great Britain, residing at Maplewood in the county of Essex, State of New ersey, have invented certain new and useful Improvements in Electron-Discharge Devices, of which the following is a full, clear, concise, and exact description.

This invention relates to electron discharge devices and has particular reference to a vacuum tube of the three electrode type.

In the use of electron discharge devices, particularly where the voltage applied between the electrodes is large, the potential difference between the various lead-in wires may be such, if special precautions are not taken, as to seriously impair if not entirely destroy the action of the device. For ex-- ample: the potential between the lead-in wires may be such as to cause sparking between the external lead-in wires; or in the case where the containing vessel has a glass stem or press through which the lead-in wires pass, the press may become heated owing to dielectric hysteresis, especially if the tube is being used as a generator or amplifier of very high frequencies. This heating effect may be sufficient to raise the temperature of the glass to a point where electrolysis sets in thereby destroying the airtight seal around the lead-in wires. This deterioration of the seal may also. occur When steady potentials are applied between the lead-in wires if the glass is heated in some other manner, as for example, during the pumping out process of the device which is carried on with the tube in an oven at a temperature of approximately 350 to 400 C.

For convenience this invention will be described in connection with a device in which the anode is supported by a collar around the stem of the vessel, the cathode and grid electrodes being insulatingly supported by the anode. Lead-in wires for the cathode and the grid may be sealed in the press at the end of the stem while the presence of the anode lead-in wire in the stem is avoided by sealing it directly and fastening it to the collar.

With such a construction, heating of the glass at the point where the lead-1n wires are sealed in the press is liable to occure due to the high alternating voltage applied between the cathode lead-in wire and the anode collar. It has been found that the intensity of the electric field between the anode collar and the sealed in portions of the cathode and grid lead-in wires may be decreased to a safe value by positioning over the end of the glass press a metallic band, which may. be connected to one of the cathode lead-in wires. This'band serves as a shield for protecting the sealed in portion of the lead-in wires from the high potential of the anode collar and thereby prevents the detrimental heating effects above mentioned.

This invention further comprises the provision of means for increasing the effective area of one or more of the external lead-in Wires whereby the strength of the field at the surface of the lead-in wires is so reduced as to prevent the above-mentioned sparking. This decrease in the strength of the field between the external lead-in wires may be accomplished either by connecting one of the lead-in wires to a metallic cylinder or band of diameter considerably larger than that of the lead-in wires, and surrounding the lead-in wires or by actually surrounding each lead-in wire with a relatively large metallic tube which is electrically connected thereto. The above described means for increasing the effective area of the leadin wires are quite satisfactory, and are preferable over actually employing lead-in wires of relatively large diameters for the reason that it is not desirable to seal in wires of' large diameter through a glass stem or ress.

The invention is illustrated in the rawing in Fig. 1 of which is shown in perspective with certain parts broken awa an electron discharge device to which t is invention has been applied; Fig. 2 is an enlarged detailed section of a modification of the application of the invention; Fig. 3 shows how the tube of this invention may be connected in a transmission circuit; and Fig. 4 shows how the grid lead-in wire may be sealed in at the base of the tube instead of being sealed in at the press.

As shown in the drawing, the invention comprises a gas tight vessel 1, preferably of glass, having a reentrant stem portion 2, a so of glass. Around the midd e portion of this stem is a metallic collar 3, preferably of nickel, to which is welded a pair of nickel T-bars 4 and 5. These bars have their u per ends welded to a metallic plate or ano e 6 which is in the form of a cylindrical open ended body, referably of nickel. Along opposite edges the anode 6, small rods of solid or hollow tubing of nickel 7 and 8 are welded. The upper and lower ends of these rods are connected to plates 9 and 10 of insulating material, preferably of lavite. Within the anode 6 there is discloseda control electrode or grid 11 formed of a plurality of spiral turns of wire which is preferably nickel wire, these turns being welded at a plurality of points throughout their len h to u -right nickel wires such as 12. '1 e rid is held in position within the anode 6 y means such as wires 13 and 14 which are connected at one end to the rid wires and at the other end are seated in the lavite plates 9 and 10. A filament or cathode 15 is supported centrally within the control electrode 11. At its upper end it is supported by two hooked wire connections 16 and 17, the upper ends of which pass loosely in apertures of lavite plate 9 and are connected at their up r end to spring members 18 and 19 whic are firmly fastened to the lavite plate 9. These members form a resilient support for the filament 15 whereby it is maintained under a constant tension during the varying temperatures to which it is subjected. The lower ends of the filament are connected to wires 20, 21 and 22, the first and last of which are normally seated in the lavite plate 10 and extend below the same through the upper end of stem 2 and pa$ out to enable electrical connections to the filament to be made. The wire 21 is anchored in the plate 10 and serves merely to engage the middle lower loop of the filament 15. Anode 6 may beconnected to an external electric circuit by lead wire 37 fastened at its upper end to T-bar 5 and sealed in between the flare of the stem; 2 and the neck of the vessel. Lead wire 25 and wire 38 provide an external connection for grid 11.

The upper end of the stem 2 at the points where the lead-in wires 23, 24 and 25 pass through it are provided with small nipples 26, 27 and 28. Closely surrounding the entire upper end of the stem 2 and in intimate contact therewith is a metal collar 29 which is connected by a wire 30 to the filament wire 22. The entire u per surface of the stem 2 is thus covered by the metal collar 29 with the exception of the small nipple extensions 26, 27 and 28. This band 29 serves as a shield for the sealed-in portions of the lead-in wires within the press and thereby prevents the undesired heating of the lass around the wires, the heating of whic tends to occur on account of the high voltage applied between the anode and cathode of the device. With the arrangement shown potentials of several thousand volts may be applied between the anode and cathode without producing injurious heating efi'ects.

f desired, the lead-in wire 25 for the grid electrode ma be removed from the influence of the e ectric field produced by the high potential on the anode lead-in wire by havin the lead-in wire 25 sealed in the base of t e vessel between the flare of the stem and the neck at a point 45 diametricall opposite the sealing-in point of the lea -in wire 37 rather than being sealed in throu h the press as shown in Fi 1. The metal ic shield 29 however, wi still be necessary in order to prevent the heating of the glass adjacent the sealed in portions of the cathode lgad-in wires.

The portions of the lead-in wires 23, 2A and -25 which pass down inside the stem portion 2 to the exterior of the tube are subject to sparking as previously mentioned. To prevent s arking between these lead-in wires, a meta lic ring 31 is placed within the stem 2 and around the lead-in wires 23, 24 and 25 and is connected to one of the lead-in wires 23, for example, by a short wire 32. This reduces the strength of the field between the lead 23 and the other lead-in wires, thereby reducing to a considerable degree the chances of Spark ing. The ring 31 is spaced from the glass ortion of the stem with a plurality of asestos washers 33. This ring 31 may be of nickel or any other suitable material.

Another means which serves as a substitute for the ring 31 above mentioned is shown in Fig. 2. This means comprises placing over the lower ends of the lead-in wires 23, 24 and 25 metal tubes such as 34, 35 and 36 which at one end are crimped tightly around the lead-in wires. It will therefore be noted that those portions of the lead-in wires 23, 24 and 25 within-the stem and adjacent the zone of collar 3 according to this new modification have been provided with surfaces the areas of which are much larger than those of the wires themselves and therefore the fields between the lead-in wires are considerably reduced over that which would be resent between the smaller leadin wires t emselves. V

The above described arrangements are of particular utility when voltages in the neighborhood of 1,000 to 15,000 volts are applied to the electrode unit of devices of the character described, whereby sparking and heating efl'ects ordinarily would tend to produce rather disastrous results upon the operation of the tube. I

Fig. 3 illustrates a circuit arrangement in which tube 1 may be employed in the well known manner as an amplifier or repeater between line sections 40 and 41.

lVhat is claimed is:

1, An electron discharge device comprising a containing vessel having a neck, a stem having a flare joined to the neck of said vessel, electrodes supported by said stem and lead wires for said electrodes, certain of said lead wires being sealed in said stem and the remainder of said lead Wires being scaled in between the flare of said stem and said neck.

2. An electron discharge device comprising a containing vessel having a neck, a stem having a flare joined to the neck of said vcssel, a cathode, a grid, and an anode, and lead wires for said grid and anode sealed in between said flare and said neck at diametrically opposite points.

3. An electron discharge device comprising a containing vessel havipg a neck, a stem having a flare joined to the neck of said vessel, electrodes supported by said stem, and a lead wire for one of said electrodes external of said stem and sealed in between the flare of said stem and said neck.

4. An electron discharge device comprising a containing vessel, a stem, an electrode above the stem, a support for said electrode having a colar portion surrounding the stem intermediate its length, a shield immediately adjacent and surrounding the end of the stem between the stem and the electrode, a leadin wire within the stem and connected to said electrode, a metallic shield around the lead-in wire within the stem in the vicinity of said collar, and a connection between the lead-in wire and both of the shields.

5. An electron discharge device comprising a containing vessel having a stem, an electrode above the stem, a metallic support for said electrode, part of said support comprising a collar surrounding the stem, shielding means immediately adjacent and surrounding the end of the stem, said shielding means lying between the end of the stem and the electrode, lead-in Wires within the stem and connected to said electrode, and a second shield within the stem and around each of the lea -in wires in the vicinity of the collar portion of said support, each of the shields being electrically connected to a lead-in wire.

6. An electron discharge device comprising a containing vessel having a stem, electrodes supported by said stem, lead-in wires for said electrodes, one of said lead-in wires rality of electrodes,

being adjacent a port-ion of one of said electrodes to which a high voltage is to be applied, a metallic shield between said portion and said lead-in wire, and a connection between said shield and one of said lead-in wires.

7. An electron discharge device comprising a containing ves'selcontaining a plulead-in wires through the wall of said vessel to said electrodes, a metallic shield substantially coverin that portion of the wall immediately a jacent the sealed in portions of said lead-in wires and a metallic connection between said shield and one of said lead-in wires.

8. An electron discharge device comprising a containing vessel having a glass stem, electrodes supported by said stem, a lead-in wire sealed in said stem for one of said electrodes, means external to said stem for providing an electrical connection for another of said electrodes, and means for preventing high potentials applied between said wire and said first means from producing a substantial heating of the glass adjacent the sealed-in portion of said wire. i

9. An electron discharge device comprising a containing vessel of glass containing a plurality of electrodes, lead-in wires for saidelectrodes sealed through the glass wall of said vessel and metallic shielding means for preventing high potentials applied between said lead-in wires from causing a substantial heating of the glass adjacent the sealed in portion of one of said-wires, said means being electrically connected to one of said 1ead-in wires.

10. An electron discharge device comprising a containing vessel having a glass stem, a plurality of electrodes in said vessel, a lead-in wire sealed in said stem for one of said electrodes, a portion of another of said electrodes being in close proximity to the sealed in portion of said lead-in wire, and shielding means between the sealed-in part of said lead-in wire and said electrode portion for preventing a substantial heating of the glass adjacent the seal when high potentials are applied to said electrodes, said shielding means being electrically connected to said lead-in wire.

11. An electron discharge device comprising a. containing vessel having a glass stem, a plurality of electrodes in said vessel, a lead-in wire sealed in said stem for one of said electrodes, a portion of another of said electrodes being located adjacent a part of said lead-in wire external to said vessel and metallic shielding means surrounding said lead-in wire for preventing electrical discharge effects from said wire when high potentials are applied to said electrodes.

12. An electron discharge device comprising a containing vessel containing a glass stem, a plurality of electrodes, lead-in wires sealed in said stem for said electrodes, and a metallic tubular member surrounding each of a plurality of said wires and electrically connected thereto, said'members being located external to said vessel.

13. An electron discharge device c0mprising a containing vessel containing an electrode unit, a stem, lead-in wires for said unit; a metallic shield between -sa.id unit and the sealed in portion of said wires,-and 1 a metallic shield for said wires on the side of said sealed in portion opposite said unit. In witness whereof, I hereunto subscribe my name this 16th day of July A. D., 1920.

WILLIAM WILSON. 

